Ohi OK as restart applicants line up

Japan's only currently operating nuclear units, Ohi 3 and 4, look set to continue running until September after a ruling from regulators in the light of new standards. Meanwhile, Tepco is to file for permission to restart two units at Kashiwazaki Kariwa.

Japan's only currently operating nuclear units, Ohi 3 and 4, look set to continue running until September after a ruling from regulators in the light of new standards. Meanwhile, Tepco is to file for permission to restart two units at Kashiwazaki Kariwa.

Ohi (Image: Kansai)

According to the Japan Atomic Industry Forum's Atoms in Japan, the Japanese Nuclear Regulatory Authority (NRA) has "largely accepted" a written evaluation concluding that there are no immediate severe safety issues at the two units under new regulatory standards that come into effect this month. The decision means that the units can continue to run until their next scheduled outage for maintenance.

Nevertheless, in its 24 June ruling, the regulator ordered Kansai to ensure that several items of equipment that were not in compliance with the new standards were rectified by the end of June. Kansai confirmed in a press release dated 1 July that all the prescribed measures had been completed.

Ohi 3 and 4 have been operating under special regulatory permission since July 2012. The units, owned and operated by Kansai, are to date the only reactors to have been allowed to restart in Japan since all of the country's nuclear power plants were taken off line for scheduled maintenance outages over the months following the Fukushima accident of 2011.

Tepco joins restart queue

Tokyo Electric Power Company (Tepco) has confirmed that it will be applying for permission to restart two units at its Kashiwazaki Kariwa plant as soon as the new regulations governing the restart of reactors idled as a result of the Fukushima accident enter into force.

The new regulations require nuclear companies to show their reactor units are prepared for extraordinary external events comparable to the natural disaster on 11 March 2011, including stronger and higher tsunami walls and waterproofing of key buildings. Additional countermeasures for accident situations must be in place, and in the longer term operators must establish a secondary control room and sources of power and water away from the reactor building to allow the plant to be controlled remotely if need be.

According to Tepco, it is ready to lodge its application for NRA assessment of Kashiwazaki Kariwa units 6 and 7 "as soon as possible" when the new regulations come into force on 8 July. The company has also said that its officials will visit Niigata Prefecture, where the plant is located, as soon as possible to talk to residents about the application and the measures it has put in place.

The seven-unit Kashiwazaki Kariwa plant, on the Sea of Japan (East Sea), was the only one of Tepco's three nuclear power stations unaffected by the March
2011 tsunami. Like other Japanese nuclear utilities, Tepco has been relying on fossil fuel to make up for the loss of its nuclear generating capacity, and the return to service of the two 1315 MWe units would go some way towards helping it to reduce its spending on costly imports of liquefied natural gas and oil.

The NRA was established in September 2012 in response to shortcomings in the Japanese regulatory system highlighted by the events at Fukushima. The NRA's new regulations covering the restart of nuclear reactors idled as a result of the 2011 Fukushima accident were finalised in late June and come into force on 8 July. The NRA has previously said that it anticipates that an application will take about six months to process.

Researched and written
by World Nuclear News